1. Field of the Invention
The present invention relates to a method for micro-contacting printing using self-assembled monolayers (SAMs) of dithiocarboxylic acids (DTCAs) and to patterned substrate formed thereby.
More particularly, the present invention relates to a method for micro-contacting printing using self-assembled monolayers (SAMs) of dithiocarboxylic acids (DTCAs) involving contacting a substrate surface with a patterned template where regions of the template are coated with a aliphatic dithiocarboxylic acid to form a pattern on the substrate surface of regions having a SAM of the DTCA and regions void of a SAM of the DTCA, depositing a material onto the patterned substrate, removing excess material and exposing the resulting patterned substrate to ambient conditions for a period of time sufficient to result in the decomposition of the DTCA SAM regions.
2. Description of the Related Art
Self-assembled monolayers (SAMs) are continuing to draw widespread interest because of their potential use in technological applications.1 Some areas of current interest include adhesion promotion/resistance,2,3 biomaterials fabrication,4-7 corrosion resistance,8,9 lithographic patterning,10,11 and microelectronics fabrication.12,13 The most thoroughly examined SAMs are those generated by the adsorption of alkanethiols on gold. Their popularity can be attributed to the ease with which they can be prepared, manipulated, and characterized.14-17 When adsorbed from solution onto gold, alkanethiols form close-packed essentially defect-free monolayer films. The sulfur atoms bind to the threefold hollow sites of Au(111) with the alkyl chains tilting approximately 30° from the normal to the surface. The overlayer structure is characterized by a (√3×√3)R 30° orientation.18,19
The structural features of SAMs on gold are dictated by two major factors: the thiol-gold interaction and the interchain interactions.14-17 The adsorbates bind to the threefold hollows to maximize the binding of sulfur to gold (see FIG. 1a); the chains tilt to maximize the interchain attractions.20,21 Consequently, we felt that it might be possible to influence the structural features of SAMs on gold by changing the nature of the binding of the adsorbate to the hexagonal lattice of gold. Specifically targeted chelating adsorbates, for example, in which the sulfur atoms are restricted in their ability to bind to the threefold hollows might generate SAMs with equilibrium structures that are different from normal alkanethiol-based SAMs. Indeed, SAMs on gold have been generated from at least two such species: aliphatic dithiocarbamates and xanthates,22,23 assuming that both sulfur atoms in the head group attach to the surface of gold (see FIG. 1b).24 To our knowledge, however, there has been no systematic comparison of the SAMs generated from these species to those generated from their normal alkanethiol analogs.
Thus, there is a need in the art for a method for micro-contacting printing where the regions to be protected are composed of SAMs of compounds that are oxidatively liable affording improved performance, lower cost and better products.